The present invention relates to tiltable slidable vehicle panel members. Preferred embodiments of the invention relate to tiltable, slidable vehicle roof panel members (i.e., vehicle roofs having an aperture closable by a sliding panel pivotable upwardly to extend from the fixed part of the roof in an "inclined" position and alternatively slidable below the fixed part of the roof to a "withdrawn" position) of the kind having a crank device mechanism comprising a rotatable crank drivingly connected with said panel to move the panel between said inclined and withdrawn positions via the closed position and being connected via a gear with a ratchet wheel cooperating with stop means to restrain rotation of the crank when the panel is in its closed position. Said roofs are referred to hereinafter as "tiltable sliding roofs of the kind referred to."
In a known tiltable sliding roof of the kind referred to (see German Offenlegeschrift No. 2,231,383) and rachet wheel has two concentric guide slots. A displaceably mounted first pin engages during the withdrawal (i.e., rearward movement) of the panel in one guide slot and is located at one end of said guide slot when the panel is in the closed position. A second pin engages during the opening movement of the roof in the other guide slot and is located at one end of said second guide slot when the roof is returned from its inclined (i.e., tilted) position into the closed position. The two pins are coupled together in such a way that only in the closed position of the roof is it possible for one pin to be removed from the guide slot associated therewith and simultaneously permitting the other pin to be inserted in the guide slot associated therewith. Quite apart from the fact that the arrangement of two guide slots and two pins coupled together by a rocking switch is costly, the main disadvantage of this known mechanism is that the user always has to operate the rocking switch in the closed position of the roof when he wishes to bring the roof from a withdrawn position via the closed position into an inclined position or from an inclined position via the closed position into a withdrawn position, so that one pin is removed from its guide slot and the other pin is inserted in its guide slot. This process can divert the attention of the driver from the road. A further disadvantage of the known mechanism is that the user can overload the mechanism when, in the manner indicated hereinbefore, he attempts to move the roof from a withdrawn position via the closed position into an inclined position or vice versa and without operating the rocking switch with the roof in the closed position, because one end of one of the two link slots forms a rigid stop member with the associated pin with the roof in the closed position. As toothed wheels normally provided in such a mechanism are generally made from plastic for cost and noise reasons, said overloading can cause breaking of teeth.
An object of the invention is to provide a crank drive mechanism for a tiltable sliding roof of the kind referred to which obviates the use of a changeover switch when moving the roof panel from a withdrawn position via the closed position into an inclined position or vice versa and prevents or at least reduces the risk of overloading of the mechanism.
According to the invention, this object is achieved by use of a resilient stop means.
In the tiltable sliding roof according to the invention, the user is made aware of the closed position of the panel through further rotation of the crank arm encountering increased resistance which is brought about in that the resilient stop means cooperates with the ratchet wheel. However, without any further measure being necessary, the user can overcome this resistance by continuing to turn the crank with a corresponding expenditure of energy, resulting in the roof being inclined or withdrawn from the closed position. Due to the resilience of the stop means, it is impossible for the user to exert a force on the mechanism which could lead to damage or destruction of parts thereof. The proposed mechanism also has a much simpler construction than the known apparatus.
The stop means preferably comprises an arresting element which in the closed position of the roof panel engages in a recess on the ratchet wheel under a resilient bias of a spring. On moving the roof panel from a closed position and in response to the resulting rotation of the ratchet wheel, the arresting element is forced out of the recess against the resilient bias of the spring and rides on the rotating ratchet wheel until it can again engage in a recess in the closed position of the roof. The force with which the arresting element is pressed against the ratchet wheel by the spring increases friction and leads to difficult operation. To obviate this, according to a feature of preferred embodiments of the invention, the path on which the arresting element rides when rotating the ratchet wheel is set back relative to the recess, so that the spring which presses the arresting element against the ratchet wheel is more relieved if the arresting element runs on the path outside the recess than when the arresting element is engaged in the recess. Alternative preferred embodiments are constructed so the path has a projection before and after the recess which must be overcome by pressing back the arresting element against the action of the spring before said arresting element can be engaged in or disengaged from the recess. Finally, according to other contemplated embodiments, any arresting element can be used whose travel is limited in such a way that it does not come into contact with the ratchet wheel outside the recess.
The recess can be provided on the ratchet wheel periphery but is preferably located in a lateral surface of the ratchet wheel. To reduce contact pressure and to avoid a one-sided loading of the ratchet wheel, it is preferable to provide two diametrically opposed recesses on the ratchet wheel to engage respective spring-loaded arresting elements in the closed position of the roof panel. The distribution of the necessary arresting force over two arresting elements reduces the pressure required of each blocking element compared with only one arresting element. As a result, it is possible to use a relatively soft material for the ratchet wheel.
To permit the arresting of the roof in the withdrawn position, the recess can cooperate with an additional arresting element provided at a corresponding location or the arresting element can cooperate with an additional recess arranged at a corresponding point on the ratchet wheel. Therefore, arresting of the roof can take place in the withdrawn position. With the transmission ratio of the gear between the crank arm and the ratchet wheel designed such that the ratchet wheel rotates by an angle of precisely 180.degree. when the roof panel is moved back from the closed into a withdrawn position, resilient arrestment of the roof panel in the withdrawn position is automatically obtained in the case of an arrangement of two diametrically opposed recesses, because in the withdrawn position the ratchet wheel assumes a position in which the two arresting elements can engage in the recesses.
Since for a complete movement sequence of the roof panel from its withdrawn position to its inclined position, a rotation angle of less than 360.degree. is available for the ratchet wheel when there is only one recess and a rotation angle of less than 180.degree. when there are two diametrically opposed recesses, a very large gearing down of, for example 1:36 is to be provided between crank arm and ratchet wheel.
In the case of a normal gear drive, very large circumferential forces occur, which greatly stress the teeth and destroy any rigid stop means, but which can be overcome without significant expenditure of energy by resilient stop means. To ensure that minimum forces occur, in the case of this extra-ordinarily large gearing down, a multistage stepping gear is provided between the crank arm and the ratchet wheel. This type of gear, which is in principle known in the case of counters with more than one place in which after in each case ten revolutions of the toothed wheel, another toothed wheel is turned by one tooth, the transmission ratio required in the present case can be obtained with limited space requirements. Normally, a two-stage stepping gear is sufficient for the necessary transmission ratio, whereby a first indexing wheel is fixed on the shaft driven by the crank arm, a second indexing wheel and a third indexing wheel rotatable therewith are arranged on an intermediate shaft and a fourth indexing wheel is rotatable with the ratchet wheel and arranged on the ratchet wheel shaft, whereby the first and second indexing wheels, as well as the third and fourth indexing wheels have teeth which only mesh over a small rotational angle. To simplify manufacture, the first and third indexing wheels, as well as the second and forth indexing wheels, should be made identical. The use of such a stepping gear is not restricted to the crank drive mechanism used in the present invention, but is also fundamentally conceivable in the case of sliding roof drives in which a large transmission ratio must be provided between a crank arm and a ratchet wheel.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a single embodiment in accordance with the present invention.